/Engine/Source/Editor/UMGEditor/Public/IHasDesignerExtensibility.h
const [TArray](API\Runtime\Core\Containers\TArray)< [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [IDesignerExtensionFactory](API\Editor\UMGEditor\IDesignerExtensionFactory) > > & GetExternalDesignerExtensionFactories() const